1. Field of the Invention
The invention relates to a device for exposing a peripheral area which exposes the peripheral area of a wafer in order to remove a photoresist which has been applied to the surface of a semiconductor wafer in the peripheral area of the wafer, wherein the outside peripheral area of the semiconductor wafer is provided with a V-shaped notch.
2. Description of the Related Art
A conventional device for exposure of a peripheral area is described below using FIG. 8, FIG. 9, FIG. 10A and FIG. 10B. FIG. 8 illustrates a schematic of the arrangement of a conventional device for exposure of a peripheral area. FIG. 9 shows a schematic of the arrangement of a controller of a conventional device for exposure of a peripheral area. FIG. 10A shows a state in which the peripheral area of a wafer is exposed by a conventional device for exposure of a peripheral area. FIG. 10B shows the exposure state of a notch area by a conventional device for exposure of a peripheral area.
In a light source device, there is a lamp 11 which emits light containing UV radiation, for example, a super-high pressure mercury lamp with a nominal wattage of 250 W. The radiant light from this lamp 11 is focused with a focusing mirror 12 on the incidence end face 13a of optical fibers 13. Between the lamp 11 and the incidence end face 13a of the optical fibers 13, there is a shutter 14 which is opened or closed by the drive of a shutter drive device 15.
When a shutter OPEN signal is sent from the operating part of the CPU within the controller 50 to the part MD3 for driving the shutter drive device, the part MD3 drives the shutter drive device 15, the shutter 14 opens and the light focused by the focusing mirror 12 is incident on the incidence end face 13a of the optical fibers 13 and is emitted as exposure light with a stipulated irradiation area S from an exposure light irradiation part 2 which is installed on the exit end face 13b of these optical fibers 13.
The exposure light irradiation part 2 is located integrally with a means 4 for edge determination (detailed below) and is movably held by a device 3 for moving the means for edge determination in the direction which is essentially perpendicular to a tangent to the edge E of the wafer W, i.e. essentially in the direction to the wafer center O (in the two directions D of the arrow in FIG. 8). The exposure light emitted from the exposure light irradiation part 2 with the stipulated exposure area S moves therefore in the same direction and by the same amount as the means 4 for edge determination.
The wafer W with an outside peripheral area which is provided with a notch N and to which a photoresist R has been applied is placed on a treatment stage 6. The wafer W is attached by an attachment means which is not shown in the drawings, for example by vacuum suction. The treatment stage 6 is rotationally held by a treatment stage rotation device 61.
When a stage rotary start signal is sent from the operating part of the CPU within the controller 50 to the part MD4 for driving the treatment stage rotation device, the part MD4 drives the treatment stage rotation device 61 and, based on the data which was input into the input part 7, such as the speed of rotation, the angle of rotation, the frequency of rotation and the like, starts rotation of the treatment stage 6.
The sequence of exposure of the peripheral area of the wafer in a conventional device for exposing a peripheral area is described as follows. First, the wafer W with an outside peripheral area provided with a notch N and to which a photoresist R has been applied is transported by a wafer transport and placement means (not shown in the drawings) and placed on the treatment stage 6 in a state in which the middle O of the wafer W and the center of rotation of the treatment stage 6 essentially agree with one another.
Next, if an exposure width adjustment start signal is sent from the operating part of the CPU within the controller 50 to the part MD2 for driving the exposure width adjustment device, the part MD2, based on data of the exposure width A (the width to be exposed proceeding from the edge E of the wafer W) which were input beforehand into the input part 7, drives the exposure width adjustment device 8 and moves the area S irradiated with the exposure light to a given position (position at which the area with the width A proceeding from the edge E of the wafer W can be exposed when the means 4 for edge determination described below captures (determines) the edge E of the wafer W).
Next, if a wafer edge determination start signal is sent from the operating part of the CPU within the controller 50 to the part MD1 for driving the device for moving the means for edge determination, the part MD1 drives the device 3 for moving the means for edge determination and moves the means 4 for edge determination in the direction to the wafer W. The determination of the position of the edge E of the wafer W is started by the means 4 for edge determination.
The controller 50 then drives the shutter drive device 15 when it receives a signal from a light receiving part 42 of the means 4 which shows that the edge E of the wafer W is determined. This causes the shutter 14 to open which irradiates the peripheral area of the wafer W via the exposure light irradiation part 2 with exposure light with the given irradiation area S. The controller 50 furthermore drives the treatment stage rotation device 61 almost simultaneously with opening of the shutter 14, and exposes the peripheral area of the wafer W by turning the wafer W with a rotational speed (which is input beforehand into the input part 7) and in an angular range (also input beforehand into the input part 7). The controller 50 controls the device 3 for moving the means for edge determination and moves the means 4 for edge determination to a position at which the means 4 for edge determination outputs a signal to the controller 50 which shows that the edge E of the wafer W is always captured. As was described above, the area S irradiated with exposure light before exposure is moved to a position at which the area with a width A proceeding from the edge E of the wafer W can be exposed when the means 4 captures the edge E of the wafer W. Moreover, upon exposure, irradiation area S is synchronized with the means 4 and moved in the same direction and by the same amount. The peripheral area of the wafer W can therefore be exposed at the exposure width A which is constant proceeding from the edge E of the wafer W.
When exposure of the peripheral area of the wafer W is completed, the controller 50 closes the shutter 14, ends rotation of the treatment stage 6 and furthermore returns the exposure light irradiation part 2 to the initial position.
A process for determining the wafer edge is now described. The means 4 for determining the edge E of the wafer W consists of the projection part 41 which projects sensor light and the light receiving part 42 which receives this sensor light and outputs to the controller 50 an analog signal which becomes larger or smaller depending on the amount of sensor light projected by the projection part 41 onto the light receiving part 42. The controller 50 amplifies the above described analog signal from the light receiving part 42 by means of an amplifier AC1. For example, in the case of complete shielding by the wafer W which has been placed on the treatment stage 6, a signal which is obtained is amplified to xe2x88x925 V and, in the case of no shielding at all, a signal which is obtained is amplified to +5 V.
The above described voltage signal which was amplified in the above described amplifier AC1 is computed in a PID circuit PC and a control signal which is used to make the above described voltage signal into a constant voltage is output to the part MD1 for driving the device for moving the means for edge determination.
The part MD1 for driving the device for moving the means for edge determination within the controller 50, drives the device 3 for moving the means for edge determination such that the means 4 for edge determination is positioned at a site at which the signal from the light receiving part 42 is, for example, 0 V, i.e. at which the sensor light from the projection part 41 is half-shielded and at which the other half is received by the light receiving part 42. The means 4 for edge determination therefore always moves to the above described position, i.e. to the position of the edge E of the wafer W.
As was described above, in a conventional device for exposing the peripheral area, the peripheral area of the wafer W is exposed by the edge E of the wafer always being captured. In the outside peripheral area, therefore, a V-shaped notch N is formed. When the wafer W, to which the photoresist R has been applied, is exposed, therefore the means 4 for edge determination in the area of the notch N also moves in a V-shape since it tries to capture the edge E of the wafer W. Since the area S which has been irradiated with exposure light and which moves synchronized with the means 4 for edge determination, in the area of the notch N also moves in a V-shape, as a result the phenomenon occurs that an area UE which is located within the wafer W and which need not be exposed is also exposed (FIG. 10B). Therefore in the vicinity of the above described area UE, there cannot be an area in which a semiconductor component (a circuit pattern or the like) is formed, thereby disadvantageously resulting in a barrier to increasing productivity for semiconductor elements.
It is therefore one object of the present invention to overcome the deficiencies of the prior art and to provide a device for exposing the peripheral area of a wafer in which an irradiation area is prevented from moving in a V-shape in a notch area of the wafer and the area which is located within the wafer and which need not be exposed is prevented from being exposed.
The above object, and other objects, are achieved by providing a device for exposing a peripheral area of a wafer to which a photoresist has been applied and having a peripheral area provided with a notch, in which by rotation of the wafer, and by simultaneous irradiation of the photoresist in the peripheral area of this wafer with exposure light, this photoresist is exposed. The device further comprises a means for edge determination which consists of a projection part for projecting sensor light and of a light receiving part for receiving this sensor light, and a device for moving the means for edge determination which moves the means for edge determination essentially in the direction to the center of the wafer. The device for exposing the peripheral area further comprises a device for moving the irradiation area which moves the above described area which has been irradiated with exposure light. The projection part projects the sensor light onto the peripheral area of the wafer and the sensor light emitted onto the edge area of the wafer is received by the light receiving part. A controller is provided which controls the device for moving the means for edge determination such that the amount of light received by this light receiving part becomes constant, and which controls the device for moving the irradiation area such that the irradiation area is moved in the same direction as the direction of motion of the means for edge determination and by the same amount as the amount of movement thereof. The controller stops operation of the device for moving the area irradiated with exposure light when it receives a signal from the means for edge determination showing the start of the notch, and restarts the operation of the device for moving the area irradiated with exposure light after a given time has passed, or when it receives a signal from the means for edge determination showing the end of the notch.
The above objects, and other objects, are also achieved by the providing a device for exposing a peripheral area, in which by rotation of the wafer with an outside peripheral area which is provided with a notch and to which a photoresist has been applied, and by simultaneous irradiation of the photoresist in the peripheral area of this wafer with exposure light, this photoresist is exposed. The device comprising a means for edge determination which consists of a projection part for projecting sensor light and of a light receiving part for receiving this sensor light, and a device for moving the means for edge determination which moves the means for edge determination essentially in the direction to the center of the wafer. The device for exposing the peripheral area also includes a device for moving the irradiation area which moves the area which has been irradiated with exposure light. The projection part projects the sensor light onto the peripheral area of the wafer and the sensor light emitted onto the edge area of the wafer is received by the light receiving part. A controller is provided to control the device for moving the means for edge determination such that the amount of light received by this light receiving part becomes constant. The controller also controls the device for moving the irradiation area such that the irradiation area is moved in the same direction as the direction of motion of the means for edge determination and by the same amount as the amount of movement thereof. A notch determination means for determining the notch is located integrally with the means for edge determination upwards of the means for edge determination. The controller stops operation of the device for moving the area irradiated with exposure light after the time following reception of a notch start signal by the notch determination means until the time at which the irradiation area reaches the notch start has passed, and restarts the operation of the device for moving the area irradiated with exposure light after a given time has passed.
In the device of the present invention for exposure of a peripheral area, the controller stops operation of the device for moving the area irradiated with exposure light when it receives a signal from the means for edge determination showing the start of the notch, and restarts the operation of the device for moving the area irradiated with exposure light after a given time has passed, or when it receives a signal from the means for edge determination showing the end of the notch. This prevents the irradiation area from moving in a V shape in the notch area of the wafer.
In the device of the present invention for exposure of a peripheral area, the controller stops operation of the device for moving the area irradiated with exposure light after a given time has passed since reception of a signal from the notch determination means showing the start of the notch, and restarts the operation of the device for moving the area irradiated with exposure light after a given time has passed. This prevents the irradiation area from moving in a V shape in the notch area of the wafer.